In or relating to creels

ABSTRACT

A creel includes a yarn package of the rotational type, which is mounted on a yarn package holder, and yarn guiding apparatus. The yarn guiding apparatus includes a first, second, third and fourth yarn guiding means. The first yarn guiding means is attached to a first end of a pivoting member. The pivoting member pivots about a pivot axis spaced from the first end. In use yarn is drawn from the yarn package and about the first, second, third and fourth yarn guiding means. The yarn is unwound by applying tension to the yarn. During unwinding, the point at which the yarn leaves the yarn package traverses axially back and forth across the yarn package. Because the first yarn guiding means is free to rotate about the pivot axis, the tension in the yarn acts to move the first guide means to a position substantially in alignment with that point.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage application of InternationalApplication No. PCT/GB2007/050024, filed on Jan. 17, 2007, which claimspriority to United Kingdom Patent Application No. 0600884.1, filed onJan. 17, 2006, the entire disclosures of which are incorporated herein.

FIELD OF THE INVENTION

This invention relates to an improvement in the delivery of yarn fromwound yarn packages on a creel. More specifically, the invention relatesto a creel having tensioned yarn guide means.

BACKGROUND OF THE INVENTION AND RELATED ART

It is normal for creels to include wound yarn packages arranged onrotating horizontal axes. EP 0567497 discloses a creel with horizontallymounted yarn packages, wherein the yarns are drawn horizontally orvertically from the yarn package and delivered via yarn guides, such asrollers and pins, to a further process, such as a fabric producingmachine. The yarn package, being relatively free to rotate, is unwoundby applying tension to the yarn.

U.S. Pat. No. 5,803,134 discloses a braking mechanism for automaticallystopping the rotating axis of each yarn package should tension in theyarn reduce due to breakage of the yarn or stoppage of the suppliedmachine. The braking mechanism comprises two horizontal rollers, thesecond of which is attached to a pivoted arm. The pivoted arm hasattached to it a flexible member that is wrapped around the axle of theyarn package. The pivoted arm is biased to rotate the second rollerdownwards, which tightens the flexible member applying a braking forceto the yarn package axle. When tension is applied to the yarn the secondroller is urged upwards about the pivot of the connecting arm, such thatthe tension of the flexible member is relaxed allowing the yarn packageto unwind.

When unwinding yarn packages, the point at which the yarn leaves theyarn package traverses back and forth across the width of the yarnpackage. In creels according to U.S. Pat. No. '134 the yarn alsotraverses back and forth across the rollers. This movement generatesaxial tension in the yarn, which creates shearing forces at the yarnpackage and rollers as the yarn traverse, in an oscillating manner, overthe lower yarn layer and roller respectively.

In some applications such as when unwinding carbon fibres, theindividual fibres that make up the yarn are sensitive to shearingforces. Fibre damage is not desirable as, amongst other things, it cancause small lengths of fibre to break off and fur up machines furtheralong the production process. This is a particular problem in ovens,where regular maintenance down time is required to clear the ovens ofdamaged fibre.

To reduce fibre damage caused by movement across the rollers, therollers are generally ceramic coated or hard anodized.

It is desirable to incorporate larger yarn packages into creels in orderto gain the maximum running time between yarn package changes. For thisreason, creels capable of unwinding yarn packages as large as 300 kg andgreater are being required. As yarn packages get larger they also getwider. Consequently, creels according to U.S. Pat. No. '134 requirewider first and second rollers capable of allowing the yarn to traversethe full width of the yarn package as it unwinds. This considerablyincreases the creel cost and size.

The traversing of the yarn across the yarn package also introducesfluctuations in the tension of the yarn, created by changes in thedistance that the yarn travels within the creel. Ideally the tensionshould be constant.

A similar problem is involved in the winding process of putting the yarnonto the yarn package. Here, it is known to use a bow bar to counteractthe change in distance as the yarn traverses across the width of theyarn package. Bow bars are not suitable for the unwinding process as alarge diameter bar would be required in order to reduce damage to theyarn caused by bending about a small radius. Furthermore, it isdesirable in the unwinding process to use rolling guides rather thanfixed guides. Thus, because a bow bar is bent, it is not practical touse a rotating bow bar.

SUMMARY OF THE INVENTION

According to one aspect of the present invention a creel comprises atleast one yarn package holder for mounting a yarn package of therotational type, wherein each yarn package holder has a correspondingyarn guide apparatus that comprises a moveable first yarn guide means,the yarn being drawn from the yarn package to the first yarn guide meansunder tension, said tension causing the first yarn guide means to movetowards (to a position substantially in alignment with) the point atwhich the yarn leaves the yarn package.

Preferably, the first yarn guide means is movable generally lengthwisein relation to the yarn package.

Suitably, each yarn guide apparatus may comprise guiding means and thefirst yarn guide means may be slidably mounted on the guiding means.Preferably, the guiding means may be arranged perpendicular to the axisof the yarn package. The guiding means may be substantially straight.Alternatively, the guiding means may be arcuate. Preferably, the guidingmeans may comprise a rod or tube of a substantially constant crosssection.

Alternatively, each yarn guide apparatus may comprise a pivoted member,wherein the first yarn guide means is attached to said pivoted member.The pivoted member may rotate about an axis and the moveable first yarnguide means may be located spaced from the pivot axis. The axis may befixed in relation to the axis of the yarn package holder. The axis maybe perpendicular to the axis of the yarn package holder and preferablythe axis of rotation may be substantially horizontal.

Preferably, each yarn guide apparatus may comprise a second yarn guidemeans, wherein the yarn may be drawn from the first yarn guide means tothe second yarn guide means.

Preferably, the pivoted member may include a first elongate section andthe first yarn guide means may be located towards a first end of theelongate section and the pivot axis may be located at a second end ofthe elongate section.

Preferably, the second yarn guide means may be attached to the pivotedmember and may preferably be located spaced closer to the rotation axisof the pivoted member than the first yarn guide means. Preferably, thelocation of the second yarn guide means may substantially correspond tothe location of the pivot axis.

Preferably, at least one of the yarn guide means may be rotatable andmay preferably comprise rollers or pulleys. Preferably, the axis of therollers may be parallel to the axis of the yarn package holder.Preferably, the rollers may retain the yarn such that the yarn does notmove significantly in the axial direction of the yarn guide. The rollersmay comprise a varying diameter to retain the yarn or alternatively maycomprise a constant diameter, wherein the yarn guide means comprises oneor more guides to retain the yarn on the roller. Preferably, the guidesmay be pins and may be ceramic coated.

Preferably, the yarn package holder may be mounted substantiallyhorizontally. Preferably, the pivot axis is mounted above the axis ofthe yarn package holder. Preferably the first yarn guide means islocated beneath the axis of the yarn package holder. Preferably, thepivoted member may comprise a second counterbalance section, which maybe arranged on an opposing side of the pivot axis to the first yarnguide means.

Preferably, the counterbalance is balanced such that the only rotationalforce applied to the yarn guide means about the pivot axis is generatedby the tension in the yarn.

Preferably, the pivot axis of the pivoted member may be arranged levelwith the centre of the width of the yarn package holder axis.Alternatively, the pivot axis may be arranged to one side of the yarnpackage holder. Preferably, the rotation radius may be substantiallylonger than the width of the yarn package holder. Preferably, the radiusmay be at least twice the width of the package holder. More preferably,the radius may be at least three times the width of the package holder.Still more preferably, the radius may be at least four times the widthof the package holder. Preferably, the first yarn guide means is locatedtoward the rear of the creel with respect to the yarn package holder.

According to a further aspect of the present invention a method ofunwinding at least one yarn package of the rotational type comprisesapplying tension to a yarn that is routed from each yarn package on acreel, wherein for each yarn package the creel comprises a yarn packageholder for mounting the yarn package and a corresponding yarn guideapparatus comprising a moveable first yarn guide means, the yarn beingdrawn from the yarn package via the first yarn guide means undertension, said tension causing the first yarn guide means to move to aposition substantially in alignment with the point at which the yarnleaves the yarn package.

The present invention includes any combination of the herein referred tofeatures or limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be carried into practice in various ways butseveral embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a rear perspective view of one yarn package of a creelaccording to the present invention and in a first position correspondingto the yarn being unwound from around the middle of the yarn package;

FIG. 2 is a rear perspective view of the creel in a second positioncorresponding to the yarn being unwound from near the left hand end ofthe yarn package;

FIG. 3 is a rear perspective view of the creel in a third positioncorresponding to the yarn being unwound from near the right hand end ofthe yarn package;

FIG. 4 is a side perspective view of the creel;

FIG. 5 is a top perspective view of the creel; and

FIG. 6 is a detailed perspective view showing part of the creelaccording to a second embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A creel generally comprises multiple yarn packages arranged on a framein a grid like manner. Each yarn package is mounted on the frame in apredetermined area, each area being substantially the same and inaccordance with the creel described herein.

As shown in FIG. 1, a preferred embodiment of a creel includes a yarnpackage 2, which is mounted on a yarn package holder 4, and yarn guidingapparatus. As shown in FIG. 4, the yarn guiding apparatus includes afirst 6, second 8, third 9, and forth 10 yarn guiding means, and apivoting member 12 that rotates about a pivot axis 14 (FIG. 1). Yarn 16is drawn from the yarn package and through the creel by the first,second, third, and forth yarn guiding means.

The yarn package 2 is of a rotational type with the yarn 16 wound in aspiral pattern back and forth across the yarn package. The yarn packageholder 4 is of any well known rotational type and the yarn package ismounted thereon such that the yarn package is free to rotate. Accordingto the first embodiment the axis of the yarn package is substantiallyhorizontal. The yarn package holder is mounted on a frame 18.

The pivoting member 12 swings about the pivot axis 14. The pivotingmember 12 is substantially elongate and is shown in the Figures as astraight rod. The first yarn guiding means 6 is attached to a first endof the pivoting member 12 by a stub axle. The pivot axis 14 is attachedto the pivoting member 12 spaced from the first yarn guiding means 6 andtowards a second end of the pivoting member. The second end of thepivoting member is on the opposing side of the pivot axis 14 to thefirst yarn guiding means 6 and comprises a counterbalance section 22.The counter balance section may be removable from the pivoting member,for instance if the creel does not provide sufficient space it may benecessary to remove the counter balance section and operate the creelwithout said section. It will be appreciated that when operating thecreel without the counterbalance section, the advantageous effect, asherein described, of the pivoting member having a zero net bendingmoment will be lost. However, by reducing the pivoting member's weightthe bending moment urging the un-balanced pivoting member to its centrepoint can be minimised. Accordingly, with sufficient tension in the yarnthe pivoting member will still be moved substantially in alignment withthe point at which the yarn leaves the yarn package. The counterbalancesection includes a rod that extends from the distal end of the pivotingmember 12 at an angle of approximately 90°. A counter balance weight 24is movably attached to the rod such that the balance of the pivotingmember can be altered. The counterbalance section operates in any wellknown method.

The pivot axis 14 is attached to the frame 18 such that the pivotingmember 12 swings about an axis. The pivot axis is arranged substantiallyperpendicular to the axis of the yarn package and in a horizontal planesuch that the pivoting member 12 swings in a vertical plane. Ideally thecounterbalance weight is arranged to act as a perfect counterbalance tothe first end such that, in isolation, the pivoting member 12 produces azero net bending moment about the pivot axis 14, such that, as willbecome clear, in use the only force acting on the pivoting member isgenerated by the tension in the yarn.

The pivot axis is shown arranged substantially in line with the centreof the width of the creel package; however, the invention would workequally with the pivot axis arranged to either side.

FIG. 4 shows the location of the pivot axis 14 and first yarn guidingmeans 6. The pivot axis is located rearwardly and upwardly of the creelpackage axis. The first yarn guide is located rearwardly and downwardlyof the creel package.

The second yarn guiding means 8 is shown in the Figures as beingattached to the pivoting member 12 at a position forward of the pivotpoint 14. However, it will be appreciated that whilst ideally the secondyarn guiding means should be located as close to the pivot position aspossible so that its movement is reduced to a minimum, the presentinvention would work equally with the second yarn guiding means attachedat any location on the pivoting member 12 or alternatively to anysuitable position on the frame.

As shown in FIG. 4, the third 9 and forth 10 yarn guiding means areattached to a braking member 26. The braking member is rotatable about arod 28 with an axis that is fixed to the frame. The third yarn guidingmeans is arranged on the braking member forward of the rod and at afirst end of the braking member. The forth yarn guiding means isattached rearwardly of the rod and at a second end of the brakingmember. A first end of a flexible member such as a rope 30 is fixed tothe braking member at the second end. The rope is arranged to wraparound a radial surface of the creel package holder 4 with its secondend fixed to the frame. The braking member is biased to rotate the thirdyarn guiding means downwardly by a spring 32. Such rotation tensions therope 30, which applies a braking force to the creel package holder toresist rotation of the creel package.

Each of the first 6, second 8, third 9 and forth 10 yarn guiding meanscomprise any well known arrangement capable of guiding the yarn aboutthe path whilst retaining the position of the yarn on the yarn guidingmeans, for example, fixed rods or rollers. The axes of the rods orrollers are arranged parallel to the axis of the yarn package. The yarnguide means are shown in FIGS. 1-6 as comprising well known pulley typerollers that have a varying diameter. The diameter of the rollerincreases from the middle, outwardly toward the radial edge. It is wellknown that the geometry of such rollers maintain the yarn position withrespect to the roller by urging the yarn toward the smallest diametersection at the centre of the roller.

In use yarn is drawn rearwardly from the yarn package 2 and about thefirst yarn guiding means 6 and then upwardly and about the second yarnguiding means 8. The yarn is then routed according to any well knowncreel layout, which, as shown in the Figures, may be forwardly and overthen under the third 9 and forth 10 yarn guiding means respectively.After the forth yarn guiding means, the yarn is guided upwardly and awayfrom the creel by further yarn guiding means and toward a productionprocess such as a converting oven or fabric producing machine.

The yarn is unwound by applying tension to the yarn. When the yarnundergoes tension, the forth yarn guiding means 10 is urged upwardlyagainst the biasing force of spring 32. This relaxes the tension in therope 30 that releases the braking force applied by it to the yarnpackage holder 4 thus allowing the yarn package holder to rotate.Consequently the yarn is unwound. Should the tension reduce or be lost,the forth yarn guiding means is urged downwardly by the spring, whichreapplies the braking force to the yarn package holder such that theyarn package does not rotate.

As tension in the yarn is applied and the yarn unwound, the point atwhich the yarn leaves the yarn package traverses axially back and forthacross the yarn package, thus generating forces in the axial directionwith respect to the yarn package. Because the first yarn guiding meansis free to rotate about the pivot axis 14 and thus to traverse acrossthe yarn package on a somewhat arcuate path, the tension forces act tomove the first yarn guiding means 6 to a position substantially inalignment with the point at which the yarn leaves the yarn package.Consequently, the yarn is drawn from the yarn package in a line that issubstantially perpendicular to the yarn package axis.

The tension moves the first yarn guiding means 6 due in part to frictionbetween the yarn and yarn guiding means but also due to the geometry ofthe pulleys. The first yarn guiding means moves to find equilibrium ofthe forces. Thus when the yarn is unwinding from near the left hand sideof the yarn package, the pivoting member 12 is urged, by the tension inthe yarn to the position shown in FIG. 2. As the yarn continues tounwind and traverses back towards the centre of the yarn package, thepivoting member moves towards the centre position shown in FIG. 1. Asthe yarn is unwound further the yarn tension urges the pivoting membertowards the position shown in FIG. 3, which shows the yarn being unwoundwhen near the right hand side of the yarn package.

It will be appreciated from the forgoing that in use the pivoting member12 rotates back and forth between the two extreme positions shown inFIGS. 2 and 3 respectively. Stops (not shown) may be used to restrictthe pivoting member from moving past the extremities of the yarnpackage, which may otherwise occur due to inertia. The pivoting membermay also comprise any well known damping means (not shown) either withinthe pivot point or acting externally on the pivoting member, for examplesprings, in order to reduce the inertia effects.

FIG. 6 shows an additional or alternative arrangement for any the yarnguiding means wherein the rollers 34 comprise a constant diameter. Insome applications, the tension in the yarn may create sufficientfriction between the yarn and roller in order to maintain the positionof the yarn on the roller, thus, in the case of the first yarn guidingmeans, creating the forces necessary to move the roller. In otherapplications this frictional force may not be sufficient and, as such,the yarn guiding means includes two rods 36, 37. The two rods are fixedwith respect to the axis of the roller and are arranged on either sideof the yarn in order to restrict the axial movement of the yarn.

In an alternative embodiment, the pivot axis 14 is arrangedperpendicular to the axis of the yarn package but inclined at an angleto the horizontal. In all instances, except the vertical, the pivotingmember 12 may still be balanced such that, in use, the only rotatingforce applied about the pivot axis is caused by the yarn tension. Wheninclined to the vertical, the arrangement still operates in accordancewith the present invention, however before moving the first yarn guidemeans, the yarn tension must first overcome the inertia of the pivotingmember. Equally, the counter balance may be arranged such that, inisolation, the pivoting member has a net bending moment urging thepivoting member towards a vertical position.

In a further embodiment, the first yarn guide means is slidably mountedon a guide member such as a rail or rod. The rod is arranged paralleland in line to the axis of the yarn package and attached at both ends tothe frame. The embodiment operates equally independent of the positionof the guide member, but will be described herein with the guide memberarranged rearwardly and downwardly of the yarn package axis. The secondyarn guide means is arranged, as in the first embodiment, rearwardly andupwardly of the yarn package axis but attached to the frame. The thirdand forth yarn guide means are arranged substantially as before and inaccordance with the first embodiment.

The first yarn guiding means is substantially in accordance with thefirst embodiment but includes a mounting hole that is coincident withthe axis of the roller. The mounting hole includes a bearing such thatthe first yarn guide is mounted on the rod with the rod being arrangedwithin the mounting hole and the bearing cooperates with the rod so thatthe yarn guide can slide axially along the rod with minimal friction. Inuse, the tension in the yarn acts to slide the yarn guide back and forthacross the rod substantially as before in the first embodiment.

The guide member may be straight or alternatively, in order tocompensate for the varying yarn length between the yarn package andsecond yarn guiding means, the guide member may be arcuate.

The creel according to the present invention has several benefits overexisting creels. The width of the yarn guiding means is reduced. Thereis also reduced variation in the yarn length, which results from theyarn traversing back and forth and is measured from the yarn package,about the first yarn guide means and to the second yarn guide means.Furthermore, the yarn is unwound without causing the yarn to traverseacross the roller.

1. A creel comprising at least one yarn package holder for mounting ayarn package of the rotational type, wherein each yarn package holderhas a corresponding yarn guide apparatus that comprises a moveable firstyarn guide means, the yarn being drawn from the yarn package to thefirst yarn guide means under tension, said tension causing the firstyarn guide means to move towards the point at which the yarn leaves theyarn package.
 2. The creel according to claim 1, in which the tensioncauses the first yarn guide means to move to a position substantially inalignment with the point at which the yarn leaves the yarn package. 3.The creel according to claim 1, in which the first yarn guide means ismovable generally lengthwise in relation to the yarn package.
 4. Thecreel according to claim 1, in which each yarn guide apparatus comprisesa pivoted member, wherein the first yarn guide means is attached to saidpivoted member.
 5. The creel according to claim 1, in which each yarnguide apparatus comprises a second yarn guide means, wherein the yarnmay be drawn from the first yarn guide means to the second yarn guidemeans and the location of the second yarn guide means substantiallycorresponds to the location of a pivot axis.
 6. The creel according toclaim 1, in which at least one of the yarn guide means is a rotatableroller.
 7. The creel according to claim 6, in which each roller retainsthe yarn such that the yarn does not move significantly in the axialdirection of the yarn guide.
 8. The creel according to claim 1, in whichthe pivoted member comprises a counterbalance, which is arranged on anopposing side of a pivot axis to the first yarn guide means.
 9. Thecreel according to claim 8, in which the counterbalance is balanced suchthat the only rotational force applied to the first yarn guide meansabout the pivot axis is generated by the tension in the yarn.
 10. Thecreel according to claim 1, in which a rotation radius is substantiallylonger than a width of the yarn package holder.
 11. A method ofunwinding at least one yarn package of the rotational type comprisingapplying tension to a yarn that is routed from each yarn package on acreel, wherein for each yarn package the creel comprises a yarn packageholder for mounting the yarn package and a corresponding yarn guideapparatus comprising a moveable first yarn guide means, the yarn beingdrawn from the yarn package via the first yarn guide means undertension, said tension causing the first yarn guide means to move to aposition substantially in alignment with the point at which the yarnleaves the yarn package.